Anterior impacted bone graft and driver instruments

ABSTRACT

Instrument and implants are disclosed which provide for insertion of an implant into an intervertebral disc space from multiple approaches to the spine. Specifically, as a preferred aspect of the invention the implant includes a tapered portion and the implant may be inserted from multiple approaches to the spine with the orientation and taper properly oriented in the disc space regardless of the approach.

REFERENCE TO RELATED APPLICATIONS

The present application is a divisional of U.S. patent application Ser.No. 11/437,392 filed May 19, 2006, a continuation of abandoned U.S.patent application Ser. No. 11/030,459 filed Jan. 5, 2005 entitled“Anterior Impacted Bone Graft and Driver Instruments”, which is adivisional of U.S. patent application Ser. No. 10/213,328 filed Aug. 6,2002 entitled “Anterior Impacted Bone Graft and Driver Instruments” andissued as U.S. Pat. No. 6,984,245, which is a continuation of PCT PatentApplication Ser. No. PCT/US01/05638 filed Feb. 22, 2001 entitled“Anterior Impacted Bone Graft and Driver Instruments” which waspublished in English under Article 21(2) and which claims the benefit ofU.S. Provisional Patent Application Ser. No. 60/183,930 filed Feb. 22,2000 entitled “Instruments and Implants for Multi-Directional Insertionof a Vertebral Spacer”. Each of the referenced applications is herebyincorporated by reference in its entirety.

BACKGROUND OF THE INVENTION

The present invention relates generally to instruments and implants forintervertebral spacing. More specifically, the present inventionprovides instruments and implants that may be utilized to providemulti-directional insertion techniques to establish and maintainintervertebral spacing. Still more preferably, the present inventionprovides implants made of bone adapted to be inserted from more than onedirection while maintaining proper orientation in the disc space.

The removal of damaged or diseased discs and restoration of disc spaceheight to treat chronic back pain and other ailments, is well-known.Spacers are often utilized to maintain or reestablish disc space heightafter removal of all or a portion of the disc. Such spacing implants mayinclude those promoting fusion between adjacent vertebral bodies, inertimplants, and artificial disc implants. Such implants are typicallydesigned to be inserted from an anterior, posterior or lateral approach.However, such implants are often designed for insertion only from one ofthe particular approaches to the spine. This is particularly true whereimplants are intended to maintain non-parallel angulation betweenadjacent vertebrae. Therefore, multiple implants each designed forinsertion from one of the various approaches to the spine must bemaintained in inventory to accommodate the various surgical demands ofeach procedure. Maintaining multiple implant designs may createinventory problems for both manufacturers and their customers. Moreover,the complications of creating multiple implants to accomplish the samedesired spacing is compounded when implants are made of a scarceresources, such as allograft bone.

Therefore, there remains a need for instruments, techniques, andimplants that reduce implant inventory without sacrificing desiredimplant configurations.

SUMMARY OF THE INVENTION

The present invention provides for instruments to implant a singleimplant design from multiple approaches to the disc space. In apreferred aspect of the present invention, instruments are provided forinserting an implant from a direct anterior approach to the spine andfrom an oblique-anterior approach to the spine.

In a further aspect of the present invention, an implant is providedthat includes features permitting insertion into the disc space frommultiple directions. In a preferred aspect of the present invention, theimplant may be configured for insertion from a direct anterior approachas well as an anterior-lateral approach to the spine. Still morepreferably, the anterior-lateral approach to the spine is from anoblique angle with respect to the sagittal plane.

In still a further aspect of the present invention, a multi-facetedimplant is provided comprising an implant body having a first pair ofsubstantially parallel side walls and a second pair of substantiallyparallel side walls. The second pair of substantially parallel sidewalls are disposed at an oblique angle with respect to the first pair ofsubstantially parallel side walls. The angulation between the first andsecond set of parallel side walls permits insertion of the implant intothe disc space from multiple directions. Further in one preferredembodiment the distance between the first pair of side walls issubstantially identical to the distance between the second pair of sidewalls. One choice is to dispose the second pair of side walls at anangle of approximately 30 degrees with respect to the first pair of sidewalls. In a more preferred aspect of the present invention, the implantbody has upper and lower bone engaging surfaces that are tapered tomaintain angulation between adjacent vertebrae. In still furtherpreferred aspects of the invention, one of each of the first and secondpair of side walls includes an insertion tool bore.

In yet a further aspect of the present invention, a method of making animplant of boney material is provided. The method comprises forming afirst pair of substantially parallel side walls on the boney material. Asecond pair of substantially parallel side walls is formed at an obliqueangle with respect to the first pair of side walls. In one aspect themethod further includes forming a plurality of driving surfaces on thedonor bone. Still more preferably, the upper and lower bone engagingsurfaces are disposed at an angle with respect to each other.

In still a further aspect of the invention an implant inserter isprovided. Preferably, the implant inserter includes anti-rotationcomponents to limit rotation of the implant about the longitudinal axisof the inserter and rotation about the axis of the implant itself. Inone preferred embodiment, the anti-rotation components comprise a pairof angled side walls on the inserter adapted to engage a pair ofcorresponding surfaces on the implant. In still a further preferredaspect, a threaded post engages a corresponding opening on the implantand the angled surfaces are spaced from the opening to limit stressplaced on the implant adjacent the opening.

These and other objects of the present invention will become apparentfrom the following description of the preferred embodiments.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of an implant according to the presentinvention.

FIG. 2( a) is a side view of the implant of FIG. 1.

FIG. 2( b) is an enlarged view of a portion of FIG. 2( a).

FIG. 3 is an end view of the implant of FIG. 1.

FIG. 4 is a cross-sectional view taken along line 4-4 of FIG. 2( a).

FIG. 5 is a top view of an implant inserter according to the presentinvention.

FIG. 6 is a side view of the implant inserter of FIG. 5.

FIG. 7 is a perspective view of a distal guide of the implant inserterof FIG. 5.

FIG. 8 is a perspective view of an implant and an implant inserteraccording to the present invention.

FIG. 9 is a top view of the combination shown in FIG. 8.

FIG. 10 is a top view of a further embodiment of an implant inserteraccording to the present invention.

FIG. 11 is a side view of the implant inserter of FIG. 10.

FIG. 12 is an end view of the distal guide of FIG. 10.

FIG. 13 is a perspective view of the distal guide of FIG. 12.

FIG. 14 is a cross-sectional view taken along line 14-14 of FIG. 12.

FIG. 15( a) is a top view of an implant and an implant inserteraccording to the present invention.

FIG. 15( b) is an enlarged perspective view of a portion of FIG. 15( a).

FIG. 16 is a top view of a further embodiment of an implant according tothe present invention.

FIG. 17 is an end view of the implant of FIG. 16.

FIG. 18 is a cross-sectional view taken along line 18-18 of FIG. 17.

FIG. 19( a) is a side view of the implant of FIG. 16.

FIG. 19( b) is a perspective view of the implant of FIG. 16.

FIG. 20( a) is a top view of a further embodiment of an implant inserteraccording to the present invention.

FIG. 20( b) is a side view of the implant inserter of FIG. 20( a).

FIG. 21( a) is a perspective view of the distal guide of the implantinserter of FIG. 20( a).

FIG. 21( b) is an end view of the distal guide of FIG. 21( a).

FIG. 21( c) is a cross-sectional view of the distal guide of FIG. 21( b)taken along line 21(c)-21(c).

FIG. 22( a) is a top view of an implant inserter and an implantaccording to the present invention.

FIG. 22( b) is an enlarged perspective view of a portion of the drawingFIG. 22( a).

FIG. 23( a) is a perspective view of an implant inserter, implant, andguide tube according to the present invention.

FIG. 23( b) is an enlarged perspective view of a portion of FIG. 23( a).

FIG. 24( a) is a perspective view of an implant positioned adjacent avertebral body according to the present invention.

FIG. 24( b) is a top view of the implant and vertebral body of FIG. 24(a).

FIG. 24( c) is a further perspective view of the implant and vertebralbody of FIG. 24( a).

FIG. 25( a) is a top view of an alternative embodiment of an implantinserter according to the present invention.

FIG. 25( b) is a side view of the implant inserter of FIG. 25( a).

FIG. 26 is a perspective view of a distal guide of the implant inserterof FIG. 25( a).

FIG. 27( a) is an end view of the distal guide of FIG. 26.

FIG. 27( b) is a side view of the distal guide of FIG. 26.

FIG. 27( c) is a rear end view of the distal guide of FIG. 26.

FIG. 28 is a cross-sectional view of the distal guide taken along line28-28 of FIG. 27( b).

FIG. 29( a) is a top view of an implant and an implant inserteraccording to the present invention.

FIG. 29( b) is an enlarged perspective view of a portion of FIG. 29( a).

FIG. 30( a) is a perspective view of an implant, implant inserter, andguide tube according to one aspect of the present invention.

FIG. 30( b) is an enlarged top view of a portion of FIG. 30( a).

FIG. 31( a) is a perspective view of an implant positioned adjacent avertebral body according to the present invention.

FIG. 31( b) is a top perspective view of the implant and vertebral bodyof FIG. 31( a).

FIG. 31( c) is a further perspective view of the implant and vertebralbody of FIG. 31( a).

DESCRIPTION OF THE PREFERRED EMBODIMENTS

For the purposes of promoting an understanding of the principles of theinvention, reference will now be made to the embodiments illustrated inthe drawings and specific language will be used to describe the same. Itwill nevertheless be understood that no limitation of the scope of theinvention is thereby intended, such alterations and furthermodifications in the illustrated devices, and such further applicationsof the principles of the invention as illustrated therein beingcontemplated as would normally occur to one skilled in the art to whichthe invention relates.

The present invention provides implants and instruments formulti-directional implantation of an intervertebral spacer. Additionalinstrumentation and techniques for disc space preparation are disclosedin Provisional Application entitled “Instruments and techniques for DiscSpace Preparation,” filed Feb. 22, 2000. The disclosure of thereferenced Provisional Application is incorporated herein by referencein its entirety. Referring now to FIGS. 1-4, there is shown an implantaccording to a preferred embodiment of the present invention. Implant 10includes an upper bone engaging surface 12, a lower bone engagingsurface 14, and a central opening 16 extending from upper surface 12 tolower surface 14. While it is contemplated that implant 10 may be formedof any suitable bio-compatible material (e.g. steel, titanium,composites, ceramics, zenograft, composite bone material, etc.), in apreferred aspect of the invention, implant 10 is formed of allograftbone. Referring specifically to FIG. 4, outline 36 represents a typicaloutline of an allograft ring suitable for use to form an implantaccording to the present invention. It will be understood that centralopening 16 conforms generally to the medullary canal, typically found inan allograft ring.

Implant 10 includes a pair of opposing side walls 24 and 26 formed insubstantial parallel alignment with longitudinal axis 64. A further pairof oblique angled side walls 20 and opposing side wall 28 are formed atan angle A5 with respect to side walls 26 and 24. In a preferredembodiment, angle A5 is approximately 30 degrees. In a preferred aspect,from driving wall 18 extends substantially perpendicular to longitudinalaxis 64 and at an angle of A4 with respect to angled surface 20. In apreferred embodiment, angle A4 is substantially 60 degrees. Implant 10includes a front face 18 and an opposing end face 30. While notrequired, front face 18 and face 30 are planar surfaces in substantiallyparallel alignment. Further, front face 18 is substantially parallel toend face 30. A first opening 40 is formed in implant 10 and isinternally threaded to receive an externally threaded post. Internallythreaded opening 40 extends substantially along longitudinal axis 64 andin substantial alignment with side walls 24 and 26. A second bore 42 hasan axis 66 extending substantially parallel to axis 64 and spaced at adistance D9 therefrom. Bore 42 is adapted to receive a substantiallysmooth pin. It will be understood that a pin extending in bore 42 willlimit the tendency of implant 10 to rotate as an externally threaded rodis inserted into threaded opening 40. In a preferred aspect, distance D9is approximately 5 mm.

Referring now to FIG. 4, front face 18 and opposing end face 30 aresubstantially parallel and spaced by distance D2. In a preferred aspect,opposing side walls 24 and 26 are substantially parallel and spaced by adistance of D3. Opposing angled walls 20 and 28 are substantiallyparallel and spaced by a distance D6. In a preferred embodiment,distances D2, D3, and D6 are approximately equal. Still more preferably,in at least one preferred embodiment adapted for implantation in thelumbar spine, distances D2, D3, and D6 are approximately 26 mm.

Referring still further to FIG. 4, an angled driving wall 22 is providedat an approximately 30 degree angle with respect to front wall 18.Internally threaded bore 44 extends through angled wall 22 along axis62. Axis 62 is substantially parallel to side walls 20 and 28.

As shown most clearly in FIG. 4, the multi-faceted implant providesthree pairs of substantially parallel side walls. A reference point 60is provided on the drawing as an indication of the starting point of theformation of the various walls of the implant. Side wall portions 32 and34 are not machined, thereby preserving at least a portion of theoriginal configuration of the donor bone. It will be understood that theamount of machining required to form an implant according to the presentinvention depends in large measure on the configuration of the donorbone available and the dimensions of the implant intended to bemanufactured from the available donor bone. As will be explained furtherherein, it is advantageous in a preferred embodiment that the maximumouter dimensions of the implant permit the implant to be inserted from adirect anterior approach to the spine, an oblique angle to the spineand, while not specifically shown in the drawings, a lateral approach tothe spine.

Dimensions of donor bone vary depending on the source of the bone, aswell as the specific location of the source of an allograft ring takenalong a bone, such as the femur. In one aspect of the invention,intended for use in the lumbar spine, it is preferred that the implanthave certain minimal dimensions for the safety and efficacy of thedevice. While such dimensions are disclosed herein, it is contemplatedthat dimensions may be altered for various implants in the lumbar,thorasic, and cervical spine without deviating from the presentinvention provided that the implant provides the desired strength andstability. Specifically, minimum dimensions are given from the surfaceof the outer side walls to central channel 16. As previously indicated,central channel 16 is preferably defined by the naturally occurringmedullary canal. However, it may be altered or increased by additionalmachining to form a channel having desired dimensions or shapes. Sidewall 19 has a dimension D5. Side wall 25 has a dimension D7. Side wall31 has a dimension D4. Side wall 27 has a dimension D8. In a preferredaspect, dimensions D5, D7, and D8 are limited to a minimum thickness of4 mm. Dimension D4 may have an even smaller minimum thickness ofapproximately 3 mm.

Referring now to FIG. 2( a), implant 10 includes end wall 30 having aheight H2 and front wall 18 having a height H1. In a preferred aspect,height H1 is substantially greater than height H2. Furthermore, opposingbone engaging surfaces 12 and 14 substantially, uniformly taper fromheight H1 at end wall 30 to height H2 at front wall 18. In a preferredembodiment, height H1 is approximately 17 mm. Further, the substantiallyuniform taper between the upper and lower surfaces 12 and 14 creates anangle A1. In a particular application, angle A1 is approximately 8degrees.

In a preferred embodiment, upper surface 12 includes buttressed ridges13 providing an anti-migration surface to engage adjacent vertebral boneupon insertion and limit movement out of the disc space. In a similarfashion, lower bone engaging surface 14 includes a plurality ofbuttressed bone engaging ridges 15. Bone engaging ridges 15 are shown ingreater detail in FIG. 2( b). The bone engaging ridges include a leadingangled surface 50 and a trailing surface 54 disposed substantiallyperpendicular to the intervening flat surface 52 disposed betweenridges. Angled surface 50 is disposed at an angle A3, which in apreferred embodiment is substantially 30 degrees. Trailing surface 54 isdisposed at an angle A2, which in a preferred embodiment issubstantially 90 degrees. Individual ridges have a height ofapproximately H3, which in a preferred embodiment is approximately 0.5mm. Further, individual ridges are spaced by a distance of approximately1.5 mm, as shown by dimension D1.

The present invention further includes an implant inserter, such as thatshown in FIGS. 5 and 6. Implant inserter 80 includes an outer shaft 82and an inner shaft 85 rotatably disposed therein. Inner shaft 85includes a thumb wheel 84 connected to its proximal end and anexternally threaded portion 90 on the distal end. Implant inserter 80further includes a proximal guide 86, a distal guide 88, and a stop 87.The proximal and distal guides are intended to guide and maintainalignment of the inserter within an outer guide sleeve (not shown) whilestop 87 provides the function of limiting further movement of theimplant inserter into the outer guide sleeve (see FIG. 23 a), therebylimiting the advancement of the implant into the disc space. While theimplant inserter is shown with features suitable for use with a guidesleeve, it is contemplated that the inserter may be used without a guidesleeve.

Distal guide 88 includes upper and lower tapered guiding surfaces 89 and95, respectively. Guide 88 also includes substantially parallel opposedside walls 91 and 93. Guide 88 has a width W1 extending between sidewalls 91 and 93. Further, with reference to FIG. 7, a substantiallysmooth pin 92 extends from opening 96 while inner shaft 85 extendsthrough opening 94 of guide 88. Guide 88 includes a substantially planarbearing wall 98 extending substantially perpendicular to thelongitudinal axis of the implant inserter.

Referring now to FIGS. 8 and 9, the implant inserter of FIGS. 5 and 6 isshown interconnected with the implant of FIGS. 1-4. Implant inserter 80is interconnected with implant 10 by threaded engagement of externallythreaded portion 90 of inner shaft 85 with the internally threadedopening 40 of implant 10. Further, pin 92 may be inserted into bore 42to limit rotation of implant 10 while externally threaded portion 90 isthreadedly inserted into internally threaded bore 40. Pin 92 also limitsrotation of the implant about its own axis as force is applied toadvance the implant into the disc space. Front face 18 is in substantialabutting engagement with bearing wall 98 such that implant 10 may beimpacted into a disc space by forcing bearing wall 98 against front face18. Furthermore, substantially parallel side walls 24 and 26 of theimplant are in substantial alignment with side walls 91 and 93 of theimplant inserter. In a preferred aspect, the width W1 of distal guide 88is substantially equal to or greater than the width D3 of implant 10.The implant inserter FIGS. 8 and 9 may be referred to as a straightinserter as it is intended to function in a preferred aspect of theinvention from a direct or straight anterior approach to the spine.

In still another aspect of the invention, an oblique inserter is shownin FIGS. 10 and 11. The oblique inserter is configured for engaging theimplant of FIGS. 1-4 to permit insertion from an oblique angle to thespine. As a general reference, this approach may be carried out byapproaching the disc space in substantial alignment with the axial planeand at an oblique angle with respect to the sagittal plane. Obliqueinserter 110 includes an outer shaft 112 and an inner shaft 115 movablydisposed therein. Inner shaft 115 includes a proximal thumb wheel 114and has a distal end 120 with an external thread pattern. Inserter 110includes proximal guide 116, distal guide 118, and stop 117. Distalguide 118 includes opposing tapered surfaces 132 and 134 tapering fromopposing upper and lower surfaces 136 and 138, respectively. Distalguide 118 has a maximum width W2 extending from opposing side surfaces122 and 124. The features of implant 110 are substantially similar tothe features of implant inserter 180 with the exception of the drivingsurfaces of distal guide 118.

Referring now to FIGS. 12-14, distal guide 118 includes a centraldriving surface 128 substantially perpendicular to longitudinal axis 131and the planes of side walls 122 and 124. Distal guide 118 furtherincludes a first oblique driving surface 126 disposed at an angle A6with respect to surface 128. In a preferred aspect, angle A6 isapproximately 30 degrees. Distal guide 118 further includes a secondangled driving surface 130 disposed at an angle A7 with respect todriving surface 126. In a preferred embodiment, angle A7 isapproximately 90 degrees.

Referring now to FIGS. 15( a) and 15(b), implant inserter 110 is shownhere connected with implant 10. Implant 10 is coupled to implantinserter 110 by engagement of externally threaded portion 120 of theinner shaft with internally threaded opening 44. Driving surfaces 126,128, and 130 of distal guide 118 substantially engage surfaces 26, 22,and 18, respectively, of implant 10. It will be understood that drivingsurfaces of distal guide 118 are configured to substantially mate withthe external surfaces of implant 10 such that force transmitted on theimplant inserter tending to urge the implant into the disc space issubstantially transmitted to implant 10. Additionally, angled side walls126 and 130 inhibit rotation of implant 10. Further, in a preferredaspect, substantially parallel side walls 20 and 28 of implant 10 are insubstantial parallel alignment and co-planar with opposing parallel sidewalls 122 and 124 of distal guide 118. Width W2 of distal portion 118 issubstantially equal to or greater than the width D6 between opposingside walls 20 and 28 of implant 10.

Referring now to FIGS. 16-19( b), a further embodiment of an implantaccording to the present invention is shown. Implant 200 includes anupper bearing surface 228 and opposing lower bearing surface 230. Eachof the upper and lower bearing surfaces include anti-migration members.In a preferred aspect of the invention, the anti-migration members arecomprised of buttressed ridges extending substantially perpendicular toside walls 212 and 220. Still more preferably, upper and lower bearingsurfaces 228 and 230 extend at an angle A25 with respect to one anotherforming a tapered implant. It is contemplated that angle A25 may have avariety of angles, but in a preferred embodiment specifically adaptedfor establishing and maintaining lumbar lordosis, angle A25 isapproximately 8 degrees. Further, the implant has a maximum height ofH20, which in a preferred aspect is approximately 21 mm.

As with the implant according to the first embodiment shown in FIG. 1,implant 200 includes two pair of opposing parallel side walls.Specifically, side wall 212 opposes substantially parallel side wall220. Similarly, angled side walls 214 and opposing angled side wall 222are in substantially parallel alignment. Side wall 222 extends at anangle A23 with respect to side wall 220. Angled side wall 214 extends atan angle A21 with respect to side wall 212. In a preferred aspect,angles A21 and A23 are substantially identical. Still more preferably,angles A21 and A23 are approximately 30 degrees. Implant 200 furtherincludes end wall 216 and unmachined portion 215 extending between endwall 216 and angled wall 214. A further unmachined portion maintainingsubstantially the natural shape of donor bone 202 includes wall portion218 extending between end wall 216 and side wall 220.

The driving walls of implant 200 have been modified in comparison to theimplant of FIG. 1. Specifically, implant 200 includes a short drive wall206 extending generally perpendicular to longitudinal axis 223. Aninternally threaded opening 224 is formed extending substantially alongand in alignment with longitudinal axis 223. It is contemplated thatdriving wall 206 may be substantially unmachined and may include arcuateportions such as those found in the naturally occurring outer portion ofdonor bone 202. Referring to FIG. 16, angled driving walls 210 and 208extend away from reference line 227 at an angle of A20 and A24,respectively. In a preferred embodiment, angles A20 and A24 aresubstantially identical. Still more preferably, angles A20 and A24 aresubstantially 18 degrees. Angled driving wall 210 further includes arecess surface 229 extending into surface 210 at an angle of A22.Preferably, angle A22 is approximately 12 degrees, thereby makingsurface 229 substantially perpendicular to angled side walls 214 and222. Referring more specifically to FIG. 18, an internally threaded bore226 is defined through the implant extending along axis 231. Axis 231extends in substantial parallel alignment with side walls 214 and 222.In a preferred aspect, implant 200 is asymmetrical about axis 231. Morespecifically, in a preferred aspect of the invention axis 231 isapproximately 12 mm from angled side wall 214 and approximately 14.5 mmfrom angled side wall 222. Implant 200 further includes central opening204, which as previously described, will typically be defined by thenaturally occurring medullary canal formed in the donor bone graft.

Referring now to FIGS. 20( a)-21(c), a straight implant inserteraccording to another aspect of the present invention is illustrated.Implant inserter 250 is substantially identical to the implant inserterof FIG. 5 with the exception of distal guide 252. Distal guide 252includes a first angled drive surface 256 and an opposing angled drivesurface 258 separated from the first drive surface by a concave surface260. Surfaces 256 and 258 each extend at an angel A26 with respect toreference line 261 (FIG. 21( c)). Reference line 261 is substantiallyperpendicular to the surface of side walls 257 and 259. In a preferredaspect, angle A26 is substantially 18 degrees to matingly engagecorresponding surfaces on implant 200. Distal guide 252 further includesan internal bore 262 extending through surface 260 adapted to receivethe inner shaft. The inner shaft has an externally threaded portion 254extending beyond distal guide 252.

Referring now to drawing FIGS. 22( a) and 22(b), implant inserter 250 isshown selectively coupled to implant 200. Distal guide 252 abuttinglyengages implant 200. More specifically, angled drive surfaces 256 and258 abuttingly engage angled drive surfaces 210 and 208, respectively.It will be understood that angled surfaces act to inhibit rotation ofimplant 200. Angled surfaces 256 and 258 limit rotation of the implantabout the longitudinal axis of the inserter as the threaded post isengaged to implant 200 and rotation of the implant about itself as forceis applied to urge the implant into the disc space. Thus, the angleddrive surfaces provide secure engagement with the implant without theneed for additional openings that may weaken the implant walls. Concavesurface 260 is intended to be spaced from naturally occurring surface206 such that machining of surface 206 is not required to provide therequisite clearance. Further, by spacing the driving walls from the wallhaving the threaded opening, force applied to the implant duringinsertion is concentrated away from the implant opening thereby havingless tendency to cause fracture. This may be particularly beneficialwhere somewhat brittle materials, such as bone or ceramics, are used toform the implant. As shown in FIGS. 22( a)-(b), with implant 200securely engaged with driver 250, opposing implant side walls 200 and220 are in substantial alignment with implant driver side walls 257 and259. It will be understood that by providing angled driving surfacesrather than a single planar drive surface, more of the naturalarchitecture of the bone may be maintained, thereby increasing thestrength of the implant. While angled drive surfaces are shown assubstantially planar surfaces it will be understood that they may alsobe arcuate, concave, convex, or complex surfaces.

Implant 200 may be inserted into a vertebral disc space properlyprepared for receipt from a direct anterior approach. As shown in FIG.23( b), a distraction window 268 is disposed adjacent a vertebral bodyV1 with distraction extensions 270 and 272 extending into the vertebraldisc space (the opposing upper vertebra is not shown). Guide tube 262 isselectively coupled to distraction window 268. Distraction window andguide tube define a substantially rectangular working channel (notshown) substantially confirming to the dimensions of the distal guide252. Inserter 250 with selectively coupled implant 200 attached theretomay then be inserted through guide tube 266 and distraction window 268and guided to the disc space. Implant inserter is slidably advanced inthe guide tube 266 with distal guide maintaining alignment until stop271 engages the distal end 273 of guide tube 266. Implant 200 willthereby be positioned in the proper location in the disc space with theintended orientation. The thumb wheel of implant inserter 250 may thenbe rotated to threadedly disengage the inserter from implant 200. Onceimplant inserter 250 has been disengaged from implant 200. The insertermay be removed from the guide tube and distraction window. Guide tube266 and distraction window 268 may then be removed from the disc space.

Referring now to FIGS. 24( a)-24(c), implant 200 is shown disposed in aprepared end plate of vertebral V1. It will be understood that anopposed vertebra is disposed above the implant creating a disc space,but the upper opposed vertebra has been removed from the illustrationfor the purpose of clarity. Implant 200 is shown disposed in channel C1defined in the end plate of vertebra V1. One method of forming channelC1 is disclosed in Provisional Application entitled “Instruments andTechniques for Disc Space Preparation,” filed on Feb. 22, 2000, which isincorporated herein by reference. Channel C1 extends in a directionextending from the anterior to the posterior portion of the vertebra andis configured for direct anterior insertion of an implant. End surface216 is shown in substantial alignment with posterior portion 274 ofchannel C1. Thus, end surface 216 is disposed substantially adjacent theposterior portion 275 of vertebra V1. Side walls 212 and 220 aredisposed laterally with respect to vertebra V1. Thus, implant 200 isdisposed in the disc space between vertebra V1 and the upper opposedvertebra (not shown) such that the taper between opposed bone engagingsurfaces 228 and 230 is in proper alignment and orientation to maintainthe appropriate angular relationship between the opposing vertebralbodies.

Referring now to FIGS. 25( a)-28, there is shown an implant inserter 300adapted for insertion of implant 200 from an anterior-oblique approachto the spine. Inserter 300 includes features also found in implantinserter 250 with the exception that distal guide 302 has beenconfigured to permit engagement with an implant for oblique insertion.Distal guide 302 includes a first angled drive surface 310 disposed atan angle A33 with respect to side wall 306. In a preferred embodiment,A33 is approximately 42 degrees. A second angled drive surface 314 isdisposed at an angle A32 with respect to side wall 308. In the preferredaspect, A32 is approximately 30 degrees. A third angled surface 312 isdisposed at an angle A30 with respect to angled drive surface 310 and anangle A31 with respect to angled drive surface 314. In a preferredembodiment, angle A30 is approximately 144 degrees and angle A31 isapproximately 108 degrees. Additionally, an internal bore 316 is formedthrough distal guide 302. Bore 316 is formed a distance D30 from sidewall 308 and a distance D31 from side wall 306. In a preferred aspect ofthe invention, D31 is greater than the distance D30 such that bore 316is offset with respect to the longitudinal axis of guide 302. Morespecifically, distance D30 is approximately 12 mm and distance D31 isapproximately 15 mm.

Referring to FIGS. 29( a) and 29(b), implant inserter 300 is shownselectively coupled to implant 200. Angled driving surfaces 310 and 314are in abutting engagement with driving surfaces 212 and 208. It will benoted that angled surface 312 and 310 have sufficient length such thatside wall 206 is not intended to be in substantial contact with theimplant driver. Further, it is contemplated that surface 312 may bespaced slightly from wall 210 to limit stress on the implant adjacentopening 226. Implant 200 is aligned with distal guide 302 such thatopposing side walls 214 and 222 are in substantial alignment with sidewalls 308 and 306, respectively, of distal guide 302. Moreover, angleddriving surfaces 310 and 314 cooperate to limit implant rotation.

Referring now to FIGS. 30( a)-31(c), a distraction window 342 isdisposed in a disc space created by vertebra V2 and an opposing uppervertebra (not shown) with distraction extensions 344 and 346 extendinginto the disc space. Distraction window 342 is positioned in the discspace from an anterior-oblique angle approach to the spine.Specifically, reference line 348 represents a direct anterior approachto the spine, in substantial alignment with the sagittal plane. In theanterior-oblique approach, distraction window 342 is positioned into thedisc space from an angled approach shown by angle A35. In a preferredembodiment, with opposing angled side walls disposed at an approximately30 degree angle, angle A35 is approximately 30 degrees. A guide tube 340is selectively coupled to distraction window 342, thereby forming asubstantially rectangular working channel into the disc space. Inserter300 with interconnected implant 200 is then inserted through guidesleeve 340 until implant 200 is disposed in the disc space in preformedchannel C2. The guide sleeve has dimensions substantially correspondingto the implant dimensions, thereby limiting the amount of tissue,vessels and other structures that must be removed or retracted forplacement of the implant. The inner shaft is then rotated to releaseimplant inserter from implant 200. The implant inserter, guide tube, anddistraction window may then be removed. The orientation of implant 200in comparison to vertebra V2 is substantially identical to theorientation of implant 200 with respect to vertebra V1 shown in FIGS.24( a)-24(c). End wall 216 is in substantial alignment with posteriorportion 274 of channel C2. End wall 216 is disposed substantiallyadjacent posterior portion 275 of vertebra V2. Further, opposed sidewalls 212 and 250 are in substantial lateral alignment with the lateralportions of vertebra V2. Thus, it will be understood that implant 200 ispositioned in the disc space with the tapering surfaces 228 and 230extending in the proper orientation to provide maintenance of angulationbetween vertebra V2 and the opposing upper vertebra (not shown).

While not shown by illustration, it will be understood that the implantsdescribed herein may be inserted from a direct lateral approach to thespine. The same orientation in the disc space may be achieved regardlessof the direction of insertion and the guiding instruments used.

Thus, the present invention provides an implant having multiple facetsor substantially parallel side walls allowing uniform orientation of theimplant in the disc space although it is inserted by multiple, oftenguided, approaches to the spine. Specifically, the embodiments of theimplants according to the present invention permit insertion from adirect anterior, oblique-anterior and a direct lateral approach to thespine. While preferred embodiments of the invention has disclosed threepair of substantially parallel side walls disposed at a various angles,it is contemplated that more than three pair of substantially parallelside walls could be utilized to provide for implant insertion from aplurality of angles. Further, while a particular angle of 30 degrees hasbeen utilized for the purposes of illustration in a preferredembodiment, it will be understood that any oblique angle might beutilized to provide for insertion from multiple approaches from thespine.

While the invention has been illustrated and described in detail in thedrawings and foregoing description, the same is to be considered asillustrative and not restrictive in character, it being understood thatonly the preferred embodiments have been shown and described and thatall changes and modifications that come within the spirit of theinvention are desired to be protected.

1-56. (canceled)
 57. An inserter for inserting a spinal implant,comprising: a distal guide having a first angled drive surface, a secondangled drive surface opposing said first drive surface, and a thirdsurface extending between said first drive surface and said second drivesurface, wherein said third surface includes a concave surface; and alocking mechanism adapted to abuttingly engage the implant against saidfirst drive surface and said second drive surface.
 58. The inserter ofclaim 57, further comprising an outer shaft coupled to said distalguide.
 59. The inserter of claim 58, wherein said locking mechanismincludes a threaded portion of an inner shaft adapted to threadedlyengage the implant.
 60. The inserter of claim 59, wherein said distalguide further includes a pair of parallel side surfaces, said firstdrive surface and said second drive surface being oriented at an angleof substantially 18 degrees with respect to a reference line that isperpendicular to said side surfaces.
 61. The inserter of claim 57,wherein said distal guide further includes a pair of parallel sidesurfaces, said first drive surface and said second drive surface beingoriented at an angle of substantially 18 degrees with respect to areference line that is perpendicular to said side surfaces.
 62. Aninserter for inserting a spinal implant, comprising: a distal guidehaving a first angled drive surface, a second angled drive surfaceopposing said first drive surface, and a third surface extending betweensaid first drive surface and said second drive surface, wherein saidthird surface includes a third angled surface; a locking mechanismadapted to abuttingly engage the implant against said first drivesurface and said second drive surface; and wherein said distal guide isadapted to insert the implant at least at an obtuse angle with respectto a spinal column.
 63. The inserter of claim 62, further comprising anouter shaft coupled to said distal guide, wherein said locking mechanismincludes a threaded portion of an inner shaft adapted to threadedlyengage the implant.
 64. The inserter of claim 63, wherein said distalguide has a central longitudinal axis extending through said outer shaftand said distal guide, said distal guide having a bore in which saidinner shaft is provided, said bore being offset with respect to saidlongitudinal axis.
 65. The inserter of claim 64, wherein said distalguide has parallelly oriented first and second sidewall surfaces, saidfirst drive surface being oriented at a first angle with respect to saidfirst sidewall surface, said second drive surface being oriented at asecond angle with respect to said second sidewall surface, and saidthird angled surface being oriented at a third angle with respect tosaid first drive surface.
 66. The inserter of claim 65, wherein saidfirst angle is approximately 42 degrees, said second angle isapproximately 30 degrees, and said third angle is approximately 144degrees.
 67. The inserter of claim 62, wherein said distal guide hasparallelly oriented first and second sidewall surfaces, said first drivesurface being oriented at a first angle with respect to said firstsidewall surface, said second drive surface being oriented at a secondangle with respect to said second sidewall surface, and said thirdangled surface being oriented at a third angle with respect to saidfirst drive surface.
 68. The inserter of claim 67, wherein said firstangle is approximately 42 degrees, said second angle is approximately 30degrees, and said third angle is approximately 144 degrees.
 69. Theinserter of claim 67, wherein said first, second and third angles aredifferent from one another.
 70. The inserter of claim 67, wherein: saiddistal guide has a central longitudinal axis; and said locking mechanismis offset with respect to said central longitudinal axis. 71-83.(canceled)